I can reassure you, I saw tattoos on the belly of girls after pregnancy and if distorted, then with proper physical activity, up to 90% returned to their original state. As mentioned earlier, you should not engage in physical activity and visit baths, saunas and take a bath during healing.
I think a lot depends on the condition of your skin, its quality, elasticity, softness, etc. I did two tattoos this year, one of them on the forearm, very delicate work. The master said that she could blur even during the healing period, but nothing like that, it looks great. And they didn't burn out at sea, neither one nor the other.
Tattoos can be a problem if you play sports during the healing period. What absolutely must not be done. Well, if the tattoo has healed well and you decide to get in shape, then nothing will happen to it. I have tattoos on my ribs and almost on my stomach. With them, I gained 10 kg, lost 15 kg. Not abruptly. For several months, nothing happened to the tattoo, and on the stomach, of course, the skin stretches much more than on the wrist. So, what success, good, high-quality tattoos and results in the gym)
It all depends on the rate of weight loss / gain. If you are not going to lose or gain 20 kilos in a month, then nothing will happen to the tattoo.